Question: Expand. If necessary, combine like terms. $(3+4x)(3-4x)=$
Notice that this expression has the following special form: $(a+b)(a-b)$ This form expands to what we call "a difference of squares": $( a+ b)( a- b)= a^2- b^2$ Using the above pattern, we get: $\begin{aligned} ( 3+{4x})( 3-{4x})&= 3^2-({4x})^2 \\\\ &=9-16x^2 \end{aligned}$